Small electronics and other devices (or components thereof) have traditionally been manufactured and assembled on a loose-parts basis. However, even with high-speed equipment, handling every part individually was inefficient. These inefficient manufacturing methods are giving way to fully automated, hands-off manufacturing processes.
Among the new manufacturing methods is reel-to-reel processing, which uses a feed reel and a take-up reel to control a continuous, indexed carrier strip, to which components are attached for manipulation and assembly, e.g., at different stations along an assembly line. The continuous strip is automatically rewound on the take-up reel when a monitor senses sufficient slack between a station and the take-up reel. The carrier strip does may be a metal, composite, or polymer strip, including a wire or cable. The completed or assembled parts or precursors may be delivered to an end user or customers still on the take-up reel or removed from the carrier strip for packaging and delivery. Such manufacturing technology is particularly well suited for electronic components such as ICs, discrete electronic devices, DIP switches, and connectors as well as for laminated assay devices as described further herein.
Reel-to-reel manufacturing often takes well-established technologies and processes to higher levels of convenience and cost reduction. Among the advantages of reel-to-reel manufacturing are the automated handling of components, lower production costs, higher volume throughput, less process error (high repeatability and quality), and consistent part orientation for ease and speed of assembly.
Quality control in reel-to-reel manufacturing is paramount. Cameras are often used to inspect up to 100% of the individual strip-mounted products. The cameras may check the part surface, shape, position, dimensions, and/or the presence or absence of a critical feature. However, the ability to detect defects does not immediately translate into the ability to discard the defective assemblies of products. Interrupting reel-to-reel manufacturing to remove defective assemblies defeats the purpose of using the high speed manufacturing process; therefore, defective assemblies often remain on the strip, to be detected and isolated at the end of the manufacturing process. Unfortunately, some defect in an assembly may be difficult to detect in the finished product, particularly where the product consists of a number of layers or subassemblies that are hidden or even physically inaccessible in the final product or component of a product, such as, for example due to lamination of components. Index marks on the strip may assist in later identifying the defective parts to be discarded; however, such index marks must be reliable to avoid discarding good products and passing defective products to consumers. Moreover, where several parts align with the same index markers, numerous parts may have to be discarded to assure that the defective part is removed.
The need exists for a method for individually marking defective assemblies that are detected during manufacturing, such that the marking may be detected at a later stage of manufacturing, even if the marking is hidden within the assembly or product.
The foregoing examples of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the drawings.